Essential knowledge for consistent fenestration specification

In addition, AW class has more stringent requirements for air leakage with a maximum of 0.5L/(s•m²) [0.10 cfm/sf] for operable compression-sealed products and 0.2 L/(s•m²) [0.04 cfm/sf] for fixed products. Both are tested at 300 Pa (6.27 psf) for infiltration and 75 Pa (1.57 psf) for exfiltration. AW class products also must undergo two water tests: ASTM E331-00 uniform static air pressure and ASTM E547-00 cyclic static air pressure at a minimum of 20 per cent of the design pressure, defined with the structural-deflection wind load test.

The greatest distinction for AW class products is AAMA 910-10 life cycle testing. Life cycle testing involves thermal cycling from -18 C (0 F) to 82 C (180 F); opening, closing, and locking cycles of 4,000 operations each; and a misuse test for operable windows and doors. AW products must pass ASTM E283 air leakage and ASTM E331 water penetrations tests at the completion of cycling. The operating sash are then subjected to a torsion test.

AW class products also require high-performance finishes. Painted finishes must comply with AAMA 2604-13 or AAMA 2605-13, and Class I anodizing must meet AAMA 611-14 standards. This aspect should not be overlooked when preparing specifications (Figure 1).

What is in the specification?

When it comes to specifying fenestration products, the most important consideration is to ensure consistency between requirements for products from Other Fenestration Assemblies, those in the scope of NAFS, and those in related divisions such as glazing and sealants.

First, regarding air leakage, it is important to validate requirements from both the NBC and the National Energy Code of Canada for Buildings 2020 (NEBC) and determine which one is applicable. Will the building be subject to continuous pressure differential because of the chimney effect, HVAC, or winds? These can be indicators for the air leakage rates and the pressure differential to specify.

Secondly, water resistance as per NBC 2020, driven rain pressure shall be determined using the climate design data and the protocol found in the CSA A440S1-19 Canadian Supplement to NAFS, as well as for Other Fenestration Assemblies.

The third and critical characteristic is structure. Does the project integrate tall or oversized fenestration products and does a deflection of more than L/175 present a concern to occupants or a risk for the glass?

Performance criteria expected of Other Fenestration Assemblies should be similar to those expected from windows integrated into these systems, or to adjoining windows in the same building. In addition to the air-water-structure trio, specification of extensive pre-construction testing may be needed for post-disaster buildings, super-tall buildings, or high-importance facilities. AW class can be an appropriate option for these situations since this PC requires additional, more stringent testing, and aligns with the Other Fenestration Assemblies’ AAMA 501 protocol (see Sidebar 3, page 3, and Sidebar 4 below).

If the project is a post-disaster building, a high-importance facility, or a highly customized design, the project-specific mock-up protocols, such as AAMA 501, may also be applied for fabrication, installation, and design validations. This approach offers the opportunity to identify and remediate potential issues during preconstruction, rather than facing costly changes on the actual building. However, no NAFS procedure specific to windows may be used for a product integrated into a mock-up that is following AAMA 501 protocols. If further job site validation is needed, AAMA suggests several protocols, but they are limited to water and air leakage because structural testing could compromise the integrity of the system or of the surroundings and are practically impossible outside of a test facility (see Sidebar 1, page 29).

Many building applications do not require extensive testing. What does a mid-rise, mixed-use complex, or a small commercial office demand of the Other Fenestrations Assemblies and windows forming its envelope? Examine NAFS and AAMA protocols to determine the actual performance needs for the project.

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